Data logger systems for a field warming experiment

据预测，由温室气体增加引起的气候变化首先发生在高纬度地区，而且发生得最快。在北方森林中，树木生长的记录已经显示出最近气候变暖的迹象。与此同时，每年被烧毁的北方森林数量呈上升趋势，特别是在加拿大西部，那里夏季干燥天气的持续时间有所增加。这些被烧毁的森林将需要在气候条件下再生，这些气候条件可能与它们在以前的森林再生周期中所经历的气候条件大不相同。持续的气候变暖将如何影响这些森林在火灾后重建的能力，特别是在成熟树木已经显示出干旱压力增加迹象的干燥地区？ 本研究旨在探讨气候变化的一个方面，土壤温度升高，可能会影响森林再生的模式，在南部育空地区的干北方森林。将建立一个土壤升温实验，利用太阳能热水循环在夏季将表层土壤升温2-4 °C。该实验将在1998年烧毁的大面积白色云杉林内的土壤湿度梯度上进行。自然幼苗建立在烧伤的模式表明，白色云杉再生非常差，在最干燥的网站在烧伤，而幼苗丰富的凉爽和潮湿的网站上面向北的斜坡和谷底。种植试验的白色云杉和其他森林的共同优势，将适用于温暖和控制地块，以测试是否土壤变暖和干燥可能是一个限制步骤，在森林再生火灾后，在这一地区。该实验将重复在干燥，潮湿和潮湿的网站，以确定是否有网站水分供应的差异影响森林再生土壤变暖的反应。实验结果将表明，北方森林干旱地区的变暖可能会改变火灾后森林更新的模式。

Climate change caused by increases in greenhouse gasses has been predicted to occur first and fastest at high latitudes. In the boreal forest, records of tree growth are already showing signs of recent climate warming. At the same time, there is an upward trend in the amount of boreal forest that burns each year, especially in western Canada, where there have been increases in the duration of dry summer weather. These burned forests will need to regenerate under climate conditions likely to be very different from what they experienced in previous cycles of forest regeneration. How will ongoing climate warming affect the ability of these forests to re-establish after fire, particularly in drier areas where mature trees are already showing signs of increased drought stress?     This research proposes to investigate how one aspect of a changing climate, increased soil temperature, may affect patterns of forest regeneration in an area of dry boreal forest in southern Yukon Territory. A soil warming experiment will be established that uses circulation of solar-heated water to warm surface soil during the summer by 2-4 °C. This experiment will be set up across a soil moisture gradient within a large area of white spruce forest that burned in 1998. Patterns of natural seedling establishment in the burn indicate that white spruce has regenerated very poorly at the driest sites in the burn, while seedlings are abundant in cooler and moister sites on north-facing slopes and valley bottoms. Planting trials of white spruce and other forest co-dominants will be applied to warmed and control plots to test whether soil warming and drying is likely to be a limiting step in forest regeneration after fire in this area. The experiment will be duplicated across dry, moist, and wet sites to determine if there differences in site moisture availability affect the response of forest regeneration to soil warming. Results of the experiment will indicate how increased warming in dry regions of boreal forest may alter patterns of forest renewal after fire.